DESCRIPTION: Sustained release antiretrovirals (ARVs) for HIV prevention have tremendous potential to reduce rates of new infections, especially among high-risk individuals. Long-acting injectable (LAI) ARVs for PrEP have the potential to address several key barriers inherent in daily oral PrEP, including obviating the need for daily adherence and reducing disclosure concerns. Following successful protection experiments in the macaque model, Phase II trials of the LAI formulation of GSK-744 will begin in 2014, to be followed by Phase III efficacy trials in 2016. The proposed project is based on the premise that identifying key structural, behavioral, and social dynamics of LAI PrEP products and programs can make a significant impact on the future success of the prevention strategy and the speed with which an effective product is rolled out to the highest risk populations. This proposal builds on the investigators' expertise and involvement in both daily oral PrEP trials and LAI PrEP trials in the US to focus on structural, behavioral, and social factors that might inform optimal delivery of long- active ARV formulations for prevention. The project takes a multi-modal approach to identifying relevant healthcare system delivery factors, provider dynamics, and patient preferences that might impact long-acting ARV intervention delivery, including gathering data from three sources: a) patients participating in Phase II and Phase III LAI PrEP trials; b) patients and providers participating in an demonstration-implementation project for oral PrEP; and c) participants and providers from a population most likely to be targeted for LAI PrEP -- young men who have sex with men (YMSM) of color at highest risk for HIV infection. By triangulating data from these three sources, this project will provide vital information to guide both demonstration projects and broader-scale implementation efforts. The specific aims of this project are to: 1) Identify structural, behaviora, and social factors that might influence patient-level factors relevant to implementation of LAI ARV formulations for HIV prevention, such as uptake, persistence, and adherence to follow-up; 2) Identify structural, behavioral and social factors that might influence systems-level factors relevant to implementation of LAI ARV formulations for HIV prevention, such as provider training, protocol development, access, referral, prescription, and monitoring; and 3) Identify specific barriers and facilitators to the implementation of an LAI PrEP HIV prevention program for one of the top priority populations in the US -- highest-risk young men who have sex with men (YMSM). Our proposed deliverables are time-linked to product development milestones and include: 1) recommendations for social and behavioral measures to include in Phase III trials; 2) empirically-based guidelines that can form a blue-print for future demonstration and implementation efforts; and 3) specific recommendations for provider education, clinical guidance, and strategies for optimizing delivery of LAI PrEP to the populations at highest risk for infection. The proposed project will ensure that we are ready to fully realize the potential of new LAI ARV technology, maximizing its ability to make a significant and sustained impact on the epidemic.